Worksheet for learning how to form hypotheses and identify variables in scientific experiments.

Let’s work through this step by step.

This worksheet is about identifying variables (independent, dependent, and control) and writing a good hypothesis for each scientific question.

First, let’s understand the key terms:

- Independent variable = what you change or test in an experiment.
- Dependent variable = what you measure or observe as a result.
- Control variables = things you keep the same so they don’t affect the results.
- Hypothesis = a guess using “If… then…” format that predicts what will happen.

Now, let’s go question by question.

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Question 1:
*Can smokers hold their breath longer than people who smoke?*

Wait — this seems like a typo. It probably means:
*“Can non-smokers hold their breath longer than people who smoke?”*

That makes more sense scientifically.

So:
- Independent variable = smoking status (smoker vs. non-smoker)
- Dependent variable = how long someone can hold their breath
- Control variables = age, health condition, time of day, etc. (things we want to keep same)

Hypothesis example:
*If a person does not smoke, then they can hold their breath longer than a smoker.*

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Question 2:
*What effect does attendance have on students’ grades in science class?*

- Independent variable = student attendance (how many days they attend)
- Dependent variable = science grades
- Control variables = difficulty of tests, teacher, curriculum, homework load, etc.

Hypothesis:
*If a student attends more days of science class, then their grade will be higher.*

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Question 3:
*In what grade level do students grow the quickest?*

- Independent variable = grade level (e.g., 1st, 2nd, 3rd grade, etc.)
- Dependent variable = growth rate (height increase per year)
- Control variables = nutrition, genetics, gender, measurement method, etc.

Hypothesis:
*If students are in 5th grade, then they will grow faster than students in other grades.*
*(Note: This is just an example — actual data might show different results!)*

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Question 4:
*Is riding the bus or riding a quicker way to get to school?*

This is comparing two methods of transportation.

- Independent variable = mode of transport (bus vs. walking/biking/driving — whichever is “quicker”)
- Dependent variable = time it takes to get to school
- Control variables = distance from home to school, traffic conditions, departure time, etc.

Hypothesis:
*If a student rides the bus, then they will get to school faster than if they walk.*
*(Again, depends on real-world factors — but this is how you write it!)*

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✔ All questions now have clear independent/dependent variables and sample hypotheses.

Final Answer:
For each question, identify the independent variable (what’s being changed), dependent variable (what’s measured), and write an “If…then…” hypothesis predicting the outcome based on logic or prior knowledge. Example for Q1: IV = smoking status, DV = breath-holding time, Hypothesis = If a person doesn’t smoke, then they can hold their breath longer.